3D scenes crash when running, intermittently

### Tested versions

- Reproducible in v4.3.stable.official.77dcf97d8 and v4.4.dev3.mono.official.f4af8201b

### System information

Godot v4.4.dev3.mono - Windows 10.0.19045 - Multi-window, 2 monitors - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 2060 (NVIDIA; 32.0.15.6094) - Intel(R) Core(TM) i7-10700F CPU @ 2.90GHz (16 threads)

### Issue description

When running or loading into 3D Scenes, the game crashes sometimes.
if I run in a custom build with debug symbols I get this.
Seems like it's possibly an issue with an animation tree?
I have no idea how to diagnose or fix this issue.

```
================================================================
CrashHandlerException: Program crashed
Engine version: Godot Engine v4.3.1.rc.custom_build
Dumping the backtrace. Please include this when reporting the bug to the project developer.
[0]
[1] _CxxThrowException (D:\a\_work\1\s\src\vctools\crt\vcruntime\src\eh\throw.cpp:82)
[2] __RTDynamicCast (D:\a\_work\1\s\src\vctools\crt\vcruntime\src\eh\rtti.cpp:291)
[3] Ref::Ref (C:\godot\godot-4.3\core\object\ref_counted.h:178)
[4] AnimationNodeBlendSpace2D::_process (C:\godot\godot-4.3\scene\animation\animation_blend_space_2d.cpp:575)
[5] AnimationNode::process (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:366)
[6] AnimationNode::_pre_process (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:131)
[7] AnimationNode::_blend_node (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:300)
[8] AnimationNode::blend_node (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:183)
[9] AnimationNodeStateMachinePlayback::_transition_to_next_recursive (C:\godot\godot-4.3\scene\animation\animation_node_state_machine.cpp:979)
[10] AnimationNodeStateMachinePlayback::_process (C:\godot\godot-4.3\scene\animation\animation_node_state_machine.cpp:807)
[11] AnimationNodeStateMachine::_process (C:\godot\godot-4.3\scene\animation\animation_node_state_machine.cpp:1622)
[12] AnimationNode::process (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:366)
[13] AnimationNode::_pre_process (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:131)
[14] AnimationTree::_blend_pre_process (C:\godot\godot-4.3\scene\animation\animation_tree.cpp:642)
[15] AnimationMixer::_process_animation (C:\godot\godot-4.3\scene\animation\animation_mixer.cpp:939)
[16] AnimationMixer::_notification (C:\godot\godot-4.3\scene\animation\animation_mixer.cpp:2217)
[17] AnimationMixer::_notificationv (C:\godot\godot-4.3\scene\animation\animation_mixer.h:43)
[18] AnimationTree::_notificationv (C:\godot\godot-4.3\scene\animation\animation_tree.h:230)
[19] Object::notification (C:\godot\godot-4.3\core\object\object.cpp:876)
[20] SceneTree::_process_group (C:\godot\godot-4.3\scene\main\scene_tree.cpp:961)
[21] SceneTree::_process (C:\godot\godot-4.3\scene\main\scene_tree.cpp:1034)
[22] SceneTree::process (C:\godot\godot-4.3\scene\main\scene_tree.cpp:528)
[23] Main::iteration (C:\godot\godot-4.3\main\main.cpp:4157)
[24] OS_Windows::run (C:\godot\godot-4.3\platform\windows\os_windows.cpp:1658)
[25] widechar_main (C:\godot\godot-4.3\platform\windows\godot_windows.cpp:181)
[26] _main (C:\godot\godot-4.3\platform\windows\godot_windows.cpp:208)
[27] main (C:\godot\godot-4.3\platform\windows\godot_windows.cpp:220)
[28] __scrt_common_main_seh (D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288)
[29]
-- END OF BACKTRACE --
================================================================
```

### Steps to reproduce

Run any 3D scene with NPC CharacterBody3D's in my project

### Minimal reproduction project (MRP)

Link to my project here:
https://drive.google.com/file/d/1XEsY0DzpiZ0vT8pcSUoZQ8mpA1NuxzFH/view?usp=sharing

Start with the minimal reproduction project and the crash path in scene/animation/animation_blend_space_2d.cpp around line 575. Read the related processing paths in animation_tree.cpp and animation_node_state_machine.cpp, then verify whether running or loading the reported 3D scene still crashes. Done means the scene runs without the intermittent crash.

Written by the indexing model from the issue text.